FIG. 1 schematically shows a structure of a liquid crystal cell of a liquid crystal display device. The liquid crystal cell comprises an array substrate, a color filter substrate, liquid crystals 10, and frame adhesive 19, wherein the array substrate and the color filter substrate are parallel to each other. The frame adhesive 19 has a rectangular frame structure, and is arranged between the array substrate and the color filter substrate. The array substrate, the color filter substrate, and the frame adhesive 19 jointly form a cell structure for accommodating the liquid crystals 10. The array substrate and the color filter substrate are adhered to each other by the frame adhesive 19, so that the liquid crystals 10 in a gap between the array substrate and the color filter substrate can be prevented from flowing out.
The array substrate comprises an array glass substrate 1 and a first film layer that is coated on the array glass substrate 1. The first film layer generally comprises a flat layer 2 that covers the array glass substrate, a silicon nitride layer 3 that covers the flat layer 2, and a first orientation film 4 that covers the silicon nitride layer 3. The color filter substrate comprises a color filter glass substrate 8 and a second film layer that is coated on the color filter glass substrate 8. The second film layer generally comprises a black matrix 7 that covers the color filter glass substrate 8, an overcoat layer 6 that covers the black matrix 7, and a second orientation film 5 that covers the overcoat layer 6.
An area of the first orientation film 4 is less than that of the silicon nitride layer 3. In this case, in the first film layer, a frame region can be formed at an outer edge of the silicon nitride layer 3 which does not overlap with the first orientation film 4. The frame adhesive 19, which is in a liquid state or a semi-fluid state before solidification, is sprayed from a nozzle and coated on a surface of the silicon nitride layer 3 along the frame region. The frame adhesive 19 generally covers edges of the first orientation film 4. Spacers 9 are distributed on the first orientation film 4, and then the color filter substrate is placed on the frame adhesive 19 and the spacers 9. The frame adhesive 19 can be solidified under irradiation of light. In general, the frame adhesive 19 is irradiated by light that is perpendicular to the array substrate from one side of the array glass substrate. In this manner, the array substrate and the color filter substrate can be adhered to each other through the frame adhesive 19.
The flat layer 2 is generally provided with driving circuits 11 in which scanning lines are integrated, and the driving circuits 11 are arranged between the frame adhesive 19 and the array glass substrate 1. With the development of narrow frame technology of display screen, the driving circuits 11 are distributed in an increasingly dense manner. As a result, the light transmittance of part of the flat layer 2 in which the driving circuits 11 are arranged drops from 45 percent to 20 percent or even lower. Consequently, the frame adhesive 19 cannot be solidified sufficiently due to the insufficient light irradiation, and thus the array substrate would be separated from the frame adhesive 19 easily.